Top down bottom up shades usually have a headrail, a bottom rail and a middle rail between the headrail and middle rail. The middle rail is moveable for substantially the entire length along which the shade may be extended. Usually this length extends from just below the headrail to a bottom most position that is adjacent the bottom rail. Window covering material extends between the middle rail and the bottom rail and is moveable between an extended fully lowered position and a retracted fully raised position, based on the positioning of the middle rail and bottom rail. The middle rail is configured to travel throughout the path of travel along which the window covering material may be moved to permit a full range of adjustment options to a user. Examples of top down bottom up shades may be appreciated from U.S. Pat. Nos. 5,839,494 and 5,791,390 and U.S. Patent Application Publication Nos. 2006/0231214 and 2011/0005690.
The full range of motion of the middle rail may pose a risk to small children as lift cords extending between the middle rail and the headrail may be exposed to the children. For example, when the middle rail is in a lowermost position adjacent the bottom rail, a child may be able to touch or interact with such exposed cords. Exposure to such cords could also result in a child becoming entangled in the cords, which can pose a strangulation danger to a child.
Prior to the present invention, the industry has not recognized the potential strangulation risk of a fully lowered top down bottom up shade. This failure to recognize the potential problem may be attributable to the fact that most of the reported child entanglements have involved Venetian blinds and Roman shades. Yet, the same risks exist in a fully lowered top down bottom up shade, particularly if the lift cords for the middle rail are free to move through the headrail.
There has been much discussion about the length that pull cords may extend from a blind without causing a risk of child entanglement. Obviously, if the child cannot reach the cord, then the cord poses no risk. Consequently, window covering manufacturers are now offering window blinds with retractable cords. It is becoming generally accepted in the industry that such retractable cords do not pose a risk of child entanglement if the cord, when fully retracted, does not extend more than twelve inches from the headrail.
A new top down bottom up shade is needed in which the middle rail cannot be lowered to a point at which the lift cords for the middle rail create a risk of child entanglement. Applying the experience and consensus concerning retractable pull cords indicates that top down bottom up shades in which the middle rail cannot be lowered more than twelve inches would not create a risk of child entanglement.